Macau Matters | Too much NaCl will kill you

Richard Whitfield

Like too many older people who have always eaten normal Western diets, I now take pills to control my too high blood pressure. If I had grown up and lived my life eating differently this would probably not be the case. Because of this issue I have been learning about about the topic, but I am not an expert so take the following explanation with a grain of salt!
Animal circulatory systems (the heart, blood, etc) need trace amounts of NaCl (sodium chloride), which we commonly call salt, to work properly. Circulatory systems move oxygen, water, nutrients and other materials throughout animal bodies so that their constituent cells can continue to function. Salt is needed to regulate the take-up of water in the body but too much salt can cause several health problems.
Plant circulatory systems operate differently and do not need salt (and they find it toxic). This is why herbivores must supplement their plant diets by separately eating salt. By contrast, carnivores get most of their salt from the flesh (and blood) that they eat. Humans are mostly omnivores and so may or may not need to supplement their diets with salt.
Salt enters our bodies when we eat it. Evolution has ensured that we eat enough salt by making it very tasty and by ensuring that adding salt to other foods makes them tastier. The problems come when we eat too much salt. To regulate the amount of salt in our bodies, our kidneys filter out excess salt and we excrete it in urine. However, our kidneys only have a limited capacity to remove salt from our bodies and this is why we get thirsty when we eat too much salt – it is our body’s way of getting us to drink more to increase the amount of water in our body thus reducing the salt concentration to the proper level but this also increases our blood pressure (because blood volume increases and more work has to be done to pump it around the body).
Not enough salt means low blood pressure which means that oxygen, water and other nutrients do not get to our cells and we die. High salt consumption means high blood pressure (because the blood volume increases after drinking and absorbing more water) which puts additional strain on our hearts, arteries, vein walls and kidneys which over time means that they will fail sooner and thus we live a somewhat shorter life.
The human body evolved to only need very small amounts of salt. We need less than 1500mg/day to live healthily. Modern processed foods – both Asian and Western –usually contain much more salt than we need because (1) adding salt to foods makes them tastier, (2) it is a very cheap way to add weight (because salt is inexpensive and absorbs water) and (3) a lot of salt makes us thirsty so we also buy lots of manufactured drinks. Many manufactured foods, including breads, breakfast cereals, processed meats, sauces and spices often contain 10-20 times the amount of salt actually needed to maintain good health. If you eat manufactured Western foods, adding no salt during cooking or at the table will only reduce your overall salt intake by 10-15%.
The message is clear, we are poisoning ourselves by eating too much salt. We need food manufacturers to very substantially reduce their use of salt, and we need to educate people to not add salt during cooking or at the table. Consumer demand is leading to a lot more “reduced salt” food products, but many of these products are still very salty. Several countries, including Portugal, have successfully run long term public education campaigns to reduce people’s salt intake. We need to do something similar in Macau.